Manufacturing process of watch glasses made of transparent elastic material



Sept. 13, E, MORF I 1.877358 MANUFACTURING PRO S OF WATCH GLASSES MADE OF NSPARE QELASTIC MATERIAL led April Patented Sept. 13, 1932 UNITEDSTATES ERNEST .MORF,

PATENT OFFICE or LA onAux-nn-roNns, SWITZERLAND, AssIGNoR To THE FI M [MEYER a STULRLI S. A., or. so nURn; S TZ RLAND uANUrAcTuRINorRocEsS or wATcII GLASSES MADE or TRANSPARENT ELASTIC MATERIAL Application filed April .9, 1931, Serial No. 528,936, and in Switzerland October 29, 1930.

The present invention relates to a manufacturing processof watch glasses made of a transparent elastic material.

It has been proposed with a view of avoid- 5 ing'the breaking of watch glasses especially of wrist watches to make such glasses for instance of a derivative of cellulose which is not inflammable and more transparent than the celluloidp I I a 7 It is necessary for securing such glasses safely to the bezel to camber the glasses, that f is to insertthe same with a slight outward bulging. The elasticity of the glass will press the rim into the border of the bezel.

In order to do this the glass was cut out heretofore in its approximate shape from a sheet of the chosen material and after having pressed it between two dies, one convex and the other concave, with a view of cambering the glass the rims werefinished to shape by means offile and hammer so as to obtain the required chamfering for holding it in the bezel. This process is very tedious. The daily turn-out of a workman is very r 2 small and the cost of a glass accordingly con- 1 siderable. r

To improve this state of things the present invention consists in determining beforehand geometrically the outline of the flat evolution of the camberedglasain cutting out a templet according to this outline preferably somewhat largerthan natural size and in cutting out according to said outline by means of a "recessed cutter the glass from the sheet of material, so that the glass after havingbeen cambered will have exactlythe required shape for fitting into the bezel without needing further help. A

Thus the main feature of the present invention is a process according to which flat blanks of transparent elastic material of cambered glasses for rectangular .bezels are so prepared thatafter the cambering of the l 45 same the so formed glasses will fit the bezel everywhere all around without needing further help.

The annexed drawing represents as an example and diagrammatically in Fig. 1 a plan of a bezel provided with an unbreakable glass,

in Fig. 2 a sectional view on line 11-11 of the Fig. 1,

in Fig. 3 a plan view of the approximate form of the evolution of the glass shown in section in Fig. 2,

in Fig. 4 a View on a larger scale of the cutter used for Working the rim and in Fig. 5 a sectional View of part of the bezel with the glass inserted.

With reference to the drawing a designates a bezel whereof a part is shown in section in Fig. 5. This bezel carries a glass 6 made of transparent and elastic material, which is fitted into the bezel after having been cambered to such an extent that the elasticity of the glass will hold it in place everywhere all around in order to give to the cambered glass a rim fitting a rectangular bezel as shown in Fig. 1 it must be out out in a flat state according to the outline shown in Fig. 3.

For each kind of bezels this outline can be determined beforehand geometrically so that it is possible to design a templet accord ing to the required outline. This templet is mounted for instance on an engravers pantograph having as a tool a cutter c with a profile according to Fig. 4.

The said pantograpli has a stop which limits exactly the path of the cutter in height. When the cutter is brought down. to the sheet d and by following the outline of the templet a glass will be detached having a shoulder e which enters into the groove of the bezel as shown in Fig. 5.

By means of a press having two dies, one convex and the other concave the cut-out glass is cambered and at the same time brought into the bezel. The pressure of the dies is now released so as to leave to the glass all liberty to enter by its elasticity into the grooves of the bezel where it will be firmly retained.

What I claim as new is:

In a manufacturing process of cambered Watch glasses of transparent elastic material especially for rectangular and other fancy bezels the process of cutting out from a plate of said material and by meansof a profiledcutter a plane pattern shaped according to geometrical calculation such that it fits in the predetermined cambered state exactly into the profiled bezel." a

In testimony whereof I affix my signature.

, ERNESTVMORF- W 

